1. Field of the Invention
The present invention relates to a light guide plate for a liquid crystal display back light and a liquid crystal display module of a car audio in use with the light guide plate, capable of preventing occurrence of a moiré phenomenon by removing a pattern on an incident light side.
2. Description of the Related Art
In general, a display device is one of key electronic components prevailing in an information (oriented) society. Particularly, a light guide plate for a backlight system of an image display device such as a liquid crystal display device is a transparent flat plate or wedge shaped plate, and reflects the light from the light source, uniformly illuminating the entire area of the light guide plate.
This type of light guide plate has been disclosed, for example, in Korean Patent Publication No. 1999-23490 and 2003-28304; European Patent Publication No. 1,134,488 A1; and Japanese Patent Publication No. 1993-264995.
Typically, the related art light guide plate is a flat shape or wedge shape plate. Also, it is usually injection molded to a transparent material in the plastic group, e.g. acryl (PMMA: PolyMethylMetaAcrylate).
FIG. 3 illustrates a related art light guide plate. In this type of light guide plate, a light emitted from a light source 30 is incident on the inside of a plate 510 through an incident side 510a of the plate, and totally reflects the inside of the plate 510. Then the reflected light is dispersed by a pattern 560 formed on the rear surface of the plate 510, and exits the front surface (exiting surface) of the plate 510. To promote the reflection and dispersion of the light, the pattern 560 has an etched or serration structure.
The most difficult thing for designing a liquid crystal display module of a car audio in use with the light guide plate 500 having the above pattern 560 is that the width of the liquid display module has a limit. Thus a lamp, which is a light source in a LCD, is typically positioned adjacent to a view area of the LCD. In fact, this has a great impact on the brightness of the backlight structure. This explains why much of the light is scattered and a moiré phenomenon occurs adjacent to the backlight, eventually deteriorating an image display quality.
Meanwhile, a flat surface 560b without a pattern 560 is formed on the rear surface of an opposite side 510b of the light guide plate 500. During an injection molding of the light guide plate 500, a pin support plate 510a for supporting and positioning an eject pin 430 is attached to the incident side 510a to protect the pattern 560. The plate surface 560 is where the eject pin 41 is positioned. However, this pin support plate 510a should be removed when taking off or unloading the molding, and in fact, it only complicates a manufacture process and creates cracks on the surface during the removal.